The present invention relates to a flow control valve for controlling a flow rate of ore fines flowing from an upper part to a lower part of a pipe line.
Conventionally, when transferring the ore fines of iron carbide, cement clinker, coal, iron ore or the like, it has often been practiced to control the flow rate of ore fines during transferring.
One known example of such a flow control valve for ore fines is a valve 50 rn such as shown in the longitudinally sectional view of FIG. 5. However, since this valve 50 operates by just opening and closing a swinging plate 51, it is not possible to stably and accurately control the quantity of ore fines because the ore fines flow from an inlet pipe 52 through not only the lower end of the swinging plate 51 but also the side edges of the plate, and the valve 50 is therefore not suitable for use as a flow control valve for accurately controlling the flow rate.
Another known example of such a flow control valve for ore fines is a rotary valve 60 such as shown in the longitudinally sectional view of FIG. 6. However, since this valve 60 has a rotor 61 which is rotating at all times, the ceaseless rotation accelerates the wear of rotating parts and shortens the lifetime. Furthermore, in case of controlling the flow rate, the rotational speed of the rotor 61 must be controlled in a variable manner, which increases the equipment cost.
To resolve these problems, the applicant of the present invention has previously filed a patent application for an invention which is disclosed in Japanese unexamined Patent Application No. 7-223698. A valve 70 for ore fines disclosed in the above patent application comprises, as shown in the longitudinally sectional view of FIG. 7, a casing 71 and a rotatable valve body 72 built into the casing 71, in which the casing 71 has a sideway inlet opening 73 continuing from a pipe installed thereon and a downward outlet opening 74 communicating with the inlet opening 73, and the valve body 72 is comprised of a first opening 75 connected in slidably rotatable fashion to the inlet opening 73 and a second opening 76 communicating with the first opening 75 so as to face the outlet opening 74.
By rotating the valve body 72 using driving means, the ore fines positioned at the inlet opening 73 is allowed to flow through the first opening 75 to the outlet opening 74 via the second opening 76, the rotation angle of the valve body 72 being controlled so that a prescribed quantity of ore fines can be discharged.
However, since the valve 70 for ore fines is designed to discharge a controlled quantity of ore fines by applying the angle of repose of the ore fines, the maximum attainable flow rate is small for the diameter of the inlet pipe, requiring a larger size valve for the required quantity of discharge. Furthermore, the structure of the valve becomes complex. Increased valve size and complex structure lead to an increase in valve cost. There is also the possibility that the ore fines may enter between sliding faces.
To resolve the above problem, according to the present invention, there is provided a flow control valve for ore fines comprising an ore fines inlet pipe whose lower end is cut at a prescribed angle and a swinging plate installed in swingable fashion to control the flow rate of ore fines by controlling the opening degree between the swinging plate and the lower end of the ore fines inlet pipe, wherein the ore fines inlet pipe is installed with its axis center tilted at an angle greater than the angle of repose of the ore fines, the swinging plate, when it keeps contact with the lower end of the ore fines inlet pipe, makes an acute angle with the axis center of the ore fines inlet pipe and the swinging plate is supported at an upper end thereof so that the support portion is positioned above the lower end opening of the ore fines inlet pipe, and an edge plate of prescribed height is provided around three sides except a free end side of the surface of the swinging plate which closes the lower end of the ore fines inlet pipe.
As described above, since the axis center of the ore fines inlet pipe is tilted at an angle greater than the angle of repose of the ore fines, the flow of ore fines can be stabilized at a slower velocity than would be in the case if the axis center were held in vertical position, and further, since the edge plate of prescribed height is provided around the three sides except the free end side of the surface of the swinging plate which closes the lower end of the ore fines inlet pipe, when the swinging plate is opened, the ore fines are allowed to flow out only from the free end side of the swinging plate within the height of the edge plate. Accordingly, the flow rate of ore fines can be controlled by restricting the flowing section of ore fines within a predetermined rectangular section. Thus, since an accurate flow control can be achieved by just controlling the opening of the swinging plate, a cheap flow control valve for ore fines can be provided that is capable of performing stable flow control of ore fines.
Since the support portion, which is the swinging center of the swinging plate, is located above the lower end opening of the ore fines inlet pipe, no sliding portions are brought into contact with the ore fines and there is no possibility of the ore fines entering between sliding faces.
Furthermore, when means for opening and closing the swinging plate that closes the lower end of the ore fines inlet pipe is provided on the back surface of the swinging plate, the flow control of ore fines can be accomplished without bringing the means for opening and closing the swinging plate into contact with the ore fines. This can provide a flow control valve for ore fines in which the opening and closing means is prevented from wearing by keeping contact with the ore fines.